[FEATURE] Let me change the location of .mcp.json and or define its config in setting.json or with environment variables

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

I'm trying to package up a reusable vscode dev container config and I don't want to scatter around settings files in the project root, I want everything tucked away under a subfolder (.devcontainer.json).

Proposed Solution

I should be able to do one of the following:

• With an env var change the location of .mcp.json to a subfolder instead of project root (like my .devcontainer folder)
• define mcp server settings directly with environment variables like I can the fields in settings.json
• configure claude's MCP config via some specific settings in its vscode extension (not ideal and would be specific only to vscode)

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

Configuration and settings

Use Case Example

• I could define multiple mcp configs in the same project and switch between them (think mono-repo)
• I could have my entire IDE config defined under .devcontainer.json subfolders and switch between them
• I could potentially have a reusable container image that contains a specific .mcp.json and point to it with an env var
• If mcp server config could be set with environment variables and with settings.json I would only have a single config file to pass to my devs that would configure all of claude

Additional Context

_No response_